Weight gain

The Wishnofsky Rule states that one pound of human fat tissue contains about 3,500 kilocalories (often simply called calories in the field of nutrition).

He concluded that a 3500 calorie excess or deficit for a person meeting his assumptions, would lead to the gain or loss, respectively, of one pound of body weight.

He noted that if the assumptions he made are not met, a deficit of 3500 calories would not necessarily equate to a pound of weight loss.

The claim has achieved the status of a rule of thumb and is repeated in numerous sources, used for diet planning by dietitians and misapplied at the population level as well.

However, the physiology of weight gain and loss is complex involving numerous hormones, body systems and environmental factors.

Other factors besides energy balance that may contribute to gaining weight include: A study, involving more than 12,000 people tracked over 32 years, found that social networks play a surprisingly powerful role in determining an individual's chances of gaining weight, transmitting an increased risk of becoming obese from wives to husbands, from brothers to brothers and from friends to friends.

[7] [8] The human microbiota facilitates fermentation of indigestible carbohydrates to short-chain fatty acids, SCFAs, contributing to weight gain.

[11] As a result, sleep deprivation over time may contribute to increased caloric intake and decreased self-control over food cravings, leading to weight gain.